There is nothing like a concealed identity to drive people wild. Aside from all those Shakespearean kings going among their people disguised as commoners, it's the basis of the classic murder mystery, in which the governing idea is that someone with whom you thought you were familiar is capable of lethal actions, right under your nose. Just as this unnerves, it also bewitches: what if you were able to unravel the clues and solve the mystery? What would that say about you?

As much as I enjoy the Guardian's Secret Footballer column, which has been running in the paper for the past 18 months or so, I must confess that I get even greater pleasure out of occasionally checking in with the website whoisthesecretfootballer.co.uk. It is there that the full obsessional nuttiness of football fans (and, by extension, of people in general, although that is debatable) is revealed. In this forum, each tiny piece of information, carefully tabulated and cross-referenced, about the unnamed Premier League footballer is analysed and subjected to verification, having been broken down into the categories "Main clues", "Other clues" and "Clues from his tweets". Leading candidates – Kevin Davies, Joey Barton, Nicky Shorey, Kevin Nolan, Jody Craddock, to name but a handful – are mapped on to this composite clue-portrait; in another corner, fans debate whether those who have been ruled out – Jason Euell, Rio Ferdinand, Paul Robinson – have been prematurely dismissed (what about a bit of misinformation designed to throw you off track?). We appear, it must be owned, to be nowhere near a definitive answer.

Beyond the extremes of fandom and the general appeal of turning detective, there is an obvious reason why the Secret Footballer should provoke such huge interest (although, in rather brilliantly unlikely fashion, we discover that TSF was inspired by an anonymous column written by an estate agent). Football is not merely our national sport; it also seems to become more mysterious the more we know about it. Acres of print, wall-to-wall moving imagery, phone-ins galore, streams of player autobiographies – and what do we really know about what takes place on the pitch, let alone in the dressing room?

Whether all your questions will have been answered by the time you get to the end of I Am the Secret Footballer is doubtful, but you'll certainly have gained many insights into the game, including a couple that I'm not sure the writer himself knew he was sharing. These are not inadvertently dropped clues, mind you – more unguarded moments that reveal a whole mind-set .

The basic biographical facts – allowing for red herrings, of course – tell us that TSF is a Premier League player who came up through non-league football rather than the academy system. (I admit here to a moment of sleuthing when, talking about the early days, he declares: "I have always had huge problems with anyone in authority". Right, I thought. Definitely Barton. It's a position I've subsequently refined.) We also know that he has played for more than one top-flight team, and that he captained at club level, an honour that he writes about particularly amusingly when he lampoons another player whose primary response to being appointed skipper was to commission the kit man to make a bespoke version of the armband with a giant C on it. We think he is white because he talks about being made an "honorary brother" by a group of black players with whom he was friendly as a young footballer. The other thing I can tell you without much fear of contradiction is that he's fond of a Jägerbomb or two and he doesn't like Robbie Savage (as in, really doesn't like him).

But TSF does like football and, more pertinently, he is as curious as many die-hard fans about what makes it tick. In the course of this book, he prods away at what creates a successful manager (not sucking up to your team to make them like you, that's for sure); what stands in the way of the sport dealing for once and all with racism and homophobia; the expectations and delusions of the supporters; the effects of the vast amounts of cash that have swirled around the game for nearly two decades; and the conduct and moral responsibilities of the youthful multi-millionaires who take to the pitch every Saturday (or Sunday, or weeknight, as the TV schedules dictate).

The cloak of anonymity allows for candour, although sometimes he's not candid enough – as in a tantalising snippet of gossip about naughtiness in a Dubai swimming pool. And a statement such as "I am told that one ex-Manchester United player turned manager has a reputation for showing his face only on Saturday for the game" isn't that thrilling unless we know who's being talked about (though it's true that we can guess).

There may also be raised eyebrows at our correspondent's near-defiance about players' pay – one of the most interesting aspects of the book. "Our wages may be well out of sync with the man in the street's, but why shouldn't they be?" he asks, before saying how fed up he is with people (like me) trotting out the cliché about money ruining the game. I don't agree with him – although I entirely take his point that few of us would turn down more money were it offered to us – but I think it illustrates a possibly unbridgeable conceptual chasm. Why, when the money keeps rolling in, does your ordinary, non-prawn-sandwich-eating punter wonder where it all went wrong?

Behind all of this, though, is a fascinating personal story, and one that doesn't want for poignancy. TSF writes powerfully of his struggle with depression and also of the gap between his upbringing and the life he's come to enjoy, a dissonance exemplified when he invites a group of his pre-football mates out for a birthday dinner and orders a £1,700 magnum of Mouton Rothschild. The evening does not go well and you feel the footballer's guilt at what he has clashing with his irritation with his friends for not joining him in his enjoyment of the finer things in life. It's a lonely place – although his pals do invite him for a pint of Guinness afterwards. I suspect a Jägerbomb may have been involved too.